The present invention relates to a picture viewer, in particular a photographic print viewer.
U.S. Pat. Nos. 4,245,417, 4,241,529, and 4,259,802 disclose picture viewers comprising a housing with a viewing window and a slider that, in use, is reciprocated into and out of the housing parallel to the plane of the window. The housing is adapted to receive a stack of pictures which are urged against the window by a bias means, e.g., a spring.
The slider, together with the retentive element and separator bar described below, functions to move the pictures in the stack sequentialy into and out of position to be viewed through the viewing window. When the slider is pushed fully into the housing, the uppermost picture of the stack of pictures may be viewed through the window. By moving the slider out of the housing, either the top or bottom picture of the stack is removed from the stack. The picture that is removed from the stack in this manner (the "separated picture") is returned to the opposite end of the stack from which it was removed to the stack by moving the slider back into the housing. By repeatedly reciprocating the slider into and out of the housing in this manner, a cyclic exchange of the picture presented at the window of the housing is achieved.
Means to implement this cyclic exchange comprises two additional elements, i.e., a separator bar and a retentive element. The separator bar extends acros the stack of pictures in the housing. On the outward stroke of the slider, the separator bar pushes all but the top or bottom picture in the stack out of the housing. That top or bottom picture is engaged by the retentive element on the outward stroke of the slider to separate that picture from the stack.
On the outward and return strokes of the slider, the separator bar passes first over and then under the separated picture, or vice versa, depending on whether the top or bottom picture in the stack is removed from the stack on the outward stroke. Appropriate spaces are, therefore, provided above and below the separator bar to accommodate the separated picture on the outward and return strokes of the slider.
The reciprocation of the slider back and forth in the above manner can cause abrupt movement of the pictures in the viewer. One consequence of such abrupt movement is that the picture that is removed from the stack of pictures when the slider is moved outwardly may become misaligned with respect to the remainder of the stack of pictures. When such misalignment occurs, there is a risk that when the user moves the slider back into the housing the exchange mechanism will become jammed and that the picture will be damaged as a result of such jamming.